1. Field of the Invention
This invention relates to a light irradiating switch apparatus.
2. Description of Related Art
Illuminated switches are used in many applications. One example is in an automobile where a number of illuminated switches may be used to control the air flow of an air conditioning system.
FIG. 5 shows an exemplary one of conventional illuminated switch apparatus of the type just mentioned. Referring to FIG. 5, the switch apparatus shown includes a key top 1, a casing 6, a printed circuit board 5 mounted at a lower end of the casing 6, a switch element 2 and two light sources such as, for example, a lamp 3 and a light emitting diode (LED) 4 all mounted on the printed circuit board 5, a light intercepting slide member 7 having the key top 1 mounted at an end thereof and having the other end fitted for sliding movement in the casing 6, and a cover 8 for covering over a bottom end of the casing 6.
The key top 1 has a body 9 molded from a resin material having a high light transmittance. A colored, light transmitting paint layer 10 is applied to a surface of the body 9, and a light intercepting outer layer 11 is formed by vacuum vapor deposition or sputtering on a surface of the light transmitting paint layer 10. The outer layer 11 is partially removed by means of a laser beam to form a first indicating portion 12 for indicating a spit hole, and both of the light intercepting paint layer 10 and outer layer 11 are partially removed by means of a laser beam to expose a transparent resin piece 13 made of an acrylic resin material to form a second indicating portion 14.
The key top 1 is integrally attached to the slide member 7.
The slide member 7 is formed in a tubular profile from a light intercepting material such as, for example, an ABS (acrylonitrile-butadiene-styrene) resin to which black pigment is added. The slide member 7 has formed in a top wall thereof a first perforation 15 for allowing light from the lamp 3 to irradiate upon the first indicating portion 12 and a second perforation 16 for allowing light from the LED 4 to irradiate upon the second indicating portion 14, and a light intercepting wall 17 is provided vertically between the two perforations 15 and 16.
A holder 19 for holding the LED 4 thereon is mounted uprightly on the printed circuit board 5 between a right side plate 18 and the light intercepting wall 17. A recessed portion 20 is formed at a portion of the holder 19 at which the holder 19 is mounted on the printed circuit board 5, and lower end portions of the light intercepting wall 17 and right side plate 18 are inserted in the recessed portion 20 of the holder 19 such that they are overlapped with a rising portion 21 of the holder 19 which defines the recessed portion 20.
Since the illuminated switch apparatus is constructed such that the end portion of the light intercepting wall 17 of the slide member 7 is inserted in the recessed portion 20 provided on the holder 19 such that, whether the key top 1 is depressed or not, the end portion of the light intercepting wall 17 is overlapped with the rising portion 21 of the holder 19, it is possible to prevent light from the lamp 3 from irradiating upon the second indicating portion 14 and also to prevent light from the LED 4 from irradiating upon the first indicating portion 12.
With the conventional illuminated switch apparatus described above, however, since the end portion of the light intercepting wall 17 of the slide member 7 is inserted in the recessed portion 20 of the holder 19 such that it is overlapped with the rising portion 21 of the holder 19, the slide member 7 must be positioned, taking a downward stroke of the key top 1 into consideration, at a location spaced upwardly by a distance equal to such stroke of the key top 1. Accordingly, the conventional illuminated switch apparatus has a drawback that the height or vertical dimension H between the top face of the key top 1 and the bottom face of the printed circuit board 5 is greater than the length of the eight intercepting wall plus the length of the downward key stroke. Besides, since the holder 19 is required, the number of parts is greater and a corresponding high production cost is required.